PART III. MAMMALIA OF THE SANTA CRUZ BEDS. 



MARSUPIALIA. 



BY 



WILLIAM J. SINCLAIR, 

 PRINCETON UNIVERSITY. 



INTRODUCTION. 



THE first descriptions of marsupials peculiar to the Santa Cruz for- 

 mation of Patagonia appeared in a brief dissertation by Dr. 

 Florentine Ameghino, issued at Buenos Aires in 1887. It soon 

 became apparent from the publication of figures in later papers by the 

 same author (Amegh., 1889, 1894) that some of these peculiar genera 

 resembled closely the pouched wolf or thylacyne of Tasmania, while 

 others were more or less like the smaller diprotodont marsupials of Aus- 

 tralia, and still others appeared to be related to the opossums of North 

 and South America. These resemblances to existing genera, so far as 

 could be determined from the figures and descriptions available, were 

 confined mainly to the teeth and to the shape of the jaw with its strongly 

 iriflected angle so characteristic of, although not entirely restricted to, 

 marsupials. 



A large amount of material illustrating this group was secured by 

 Messrs. Hatcher and Peterson and we are now able, for the first time, to 

 ascertain what these animals were like and whether or not they were 

 related to existing forms. 



It was originally planned that Mr. Hatcher should contribute this part 

 to the series of volumes describing the magnificent collections which his 

 energy and devotion to science have brought together in the museum of 

 Princeton University. His untimely death necessitated a transfer of the 

 work which was to have been his to other hands, and, at the request of 

 Professor Scott, it was undertaken by the writer. 



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